Cohomological tautness for Riemannian foliations

In this paper we present some new results on the tautness of Riemannian foliations in their historical context. The first part of the paper gives a short history of the problem. For a closed manifold, the tautness of a Riemannian foliation can be characterized cohomologically. We extend this cohomological characterization to a class of foliations which includes the foliated strata of any singular Riemannian foliation of a closed manifold

Seasonal changes in plankton respiration and bacterial metabolism in a temperate shelf sea

The seasonal variability of plankton metabolism indicates how much carbon is cycling within a system, as well as its capacity to store carbon or export organic matter and CO2 to the deep ocean. Seasonal variability between November 2014, April 2015 and July 2015 in plankton respiration and bacterial (Bacteria+Archaea) metabolism is reported for the upper and bottom mixing layers at two stations in the Celtic Sea, UK. Upper mixing layer (UML, >75 m in November, 41 - 70 m in April and ~50 m in July) depth-integrated plankton metabolism showed strong seasonal changes with a maximum in April for plankton respiration (1.2- to 2-fold greater compared to November and July, respectively) and in July for bacterial production (2-fold greater compared to November and April). However UML depth-integrated bacterial respiration was similar in November and April and 2-fold lower in July. The greater variability in bacterial production compared to bacterial respiration drove seasonal changes in bacterial growth efficiencies, which had maximum values of 89 % in July and minimum values of 5 % in November. Rates of respiration and gross primary production (14C-PP) also showed different seasonal patterns, resulting in seasonal changes in 14C-PP:CRO2 ratios. In April, the system was net autotrophic (14C-PP:CRO2 > 1), with a surplus of organic matter available for higher trophic levels and export, while in July balanced metabolism occurred (14C-PP:CRO2 = 1) due to an increase in plankton respiration and a decrease in gross primary production. Comparison of the UML and bottom mixing layer indicated that plankton respiration and bacterial production were higher (between 4 and 8-fold and 4 and 7-fold, respectively) in the UML than below. However, the rates of bacterial respiration were not statistically different (p > 0.05) between the two mixing layers in any of the three sampled seasons. These results highlight that, contrary to previous data from shelf seas, the production of CO2 by the plankton community in the UML, which is then available to degas to the atmosphere, is greater than the respiratory production of dissolved inorganic carbon in deeper waters, which may contribute to offshore export

A Middle Palaeolithic wooden digging stick from Aranbaltza III, Spain

Aranbaltza is an archaeological complex formed by at least three open-air sites. Between 2014 and 2015 a test excavation carried out in Aranbaltza III revealed the presence of a sand and clay sedimentary sequence formed in floodplain environments, within which six sedimentary units have been identified. This sequence was formed between 137±50 ka, and includes several archaeological horizons, attesting to the long-term presence of Neanderthal communities in this area. One of these horizons, corresponding with Unit 4, yielded two wooden tools. One of these tools is a beveled pointed tool that was shaped through a complex operational sequence involving branch shaping, bark peeling, twig removal, shaping, polishing, thermal exposition and chopping. A use-wear analysis of the tool shows it to have traces related with digging soil so it has been interpreted as representing a digging stick. This is the first time such a tool has been identified in a European Late Middle Palaeolithic context; it also represents one of the first well-preserved Middle Palaeolithic wooden tool found in southern Europe. This artefact represents one of the few examples available of wooden tool preservation for the European Palaeolithic, allowing us to further explore the role wooden technologies played in Neanderthal communities

Análisis operacional de molinos de campo eléctrico como sistemas de alerta de tormentas eléctricas en colombia

Medidas de campo electrostático realizadas en Bogotá durante episodios de tormenta en noviembre de 2010 (típicamente temporada de lluvias dada por el paso de la zona de confluencia intertropical por el centro de Colombia) fueron usadas para estudiar y analizar las características operacionales más importantes de un sensor de campo electrostático aislado. Las distancias de cada descarga nube-tierra con respecto al sensor obtuvieron a partir de los datos suministrados por el SID (Sistema de Información de Descargas). Los DE en función de la distancia permitieron definir un modelo de carga puede ser utilizado como sistema de referencia para la calibración de otros sensores de campo electrostático a ser implementados en sistemas de alerta de tormentas eléctricas.Electrostatic field measurements taken in Bogotá, Colombia, during thunderstorms in November (the rainy season due to inter-tropical confluence zone over central Colombia) were used to study the performance of an isolated electric field sensor and analyse its most important operational characteristics. The distances from each flash to the studied sensor were obtained by using the Colombian lightning location system. The DE cf distance ratio led to defining a charge model which could be used as a reference for calibrating other electrostatic field sensors to be used as lightning warning systems

Operational analysis of electric field mills as lightning warning systems in Colombia

Electrostatic field measurements taken in Bogotá, Colombia, during thunderstorms in November (the rainy season due to inter-tropical confluence zone over central Colombia) were used to study the performance of an isolated electric field sensor and analyse its most important operational characteristics. The distances from each flash to the studied sensor were obtained by using the Colombian lightning location system. The DE cf distance ratio led to defining a charge model which could be used as a reference for calibrating other electrostatic field sensors to be used as lightning warning systems

Operational analysis of electric field mills as lightning warning systems in Colombia

Electrostatic field measurements taken in Bogotá, Colombia, during thunderstorms in November (the rainy season due to inter-tropical confluence zone over central Colombia) were used to study the performance of an isolated electric field sensor and analyse its most important operational characteristics. The distances from each flash to the studied sensor were obtained by using the Colombian lightning location system. The DE cf distance ratio led to defining a charge model which could be used as a reference for calibrating other electrostatic field sensors to be used as lightning warning systems.Medidas de campo electrostático realizadas en Bogotá durante episodios de tormenta en noviembre de 2010 (típicamente temporada de lluvias dada por el paso de la zona de confluencia intertropical por el centro de Colombia) fueron usadas para estudiar y analizar las características operacionales más importantes de un sensor de campo electrostático aislado. Las distancias de cada descarga nube-tierra con respecto al sensor obtuvieron a partir de los datos suministrados por el SID (Sistema de Información de Descargas). Los DE en función de la distancia permitieron definir un modelo de carga puede ser utilizado como sistema de referencia para la calibración de otros sensores de campo electrostático a ser implementados en sistemas de alerta de tormentas eléctricas

Spatially Offset Raman Spectroscopy for Characterization of a Solid-State System

Solid-state batteries represent a promising technology in the field of high-energy-density and safe storage systems. Improving the understanding of how defects form within these cells would greatly facilitate future development, which would be best served by applying nondestructive analytical tools capable of characterization of the key components and their changes during cycling and/or aging. Spatially offset Raman spectroscopy (SORS) represents a potentially useful technique, but currently there is a lack of knowledge regarding its use in this field. To fill this gap, we present an investigation into the use of simple defocused micro-SORS on systems constructed using typical components found within solid-state cells. By analyzing the constituents and the assembled system, it was possible to obtain depth profiling spectra and show that spectra may be obtained from layers which are normally obscured, demonstrating the technique’s potential for nondestructive chemical analysis of the subsurface. In this way, the results presented validate the potential of micro-SORS as a technique to develop to support future solid-state battery development, as well as the nondestructive battery analytical field